Leaf beetles are one of the largest families of beetles in the world fauna. Some of the numerous different species have an astonishingly beautiful appearance. As herbivorous animals, however, many of them also have pest status for gardeners and farmers. We introduce you to the most important types.

The red-necked grain beetle is just one of around 50,000 different leaf beetle species

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  1. Identification of leaf beetles
  2. Important Species
  3. Fight leaf beetles
  4. frequently asked Questions

    5. Zoological identification of the leaf beetle

    With a total of around 50,000 species described so far, the leaf beetles, zoological Chrysomelidae, form one of the largest beetle families in the world. They are distributed in all zoolographic areas of the world with the exception of the arctic zones. In Germany, around 520 of the 50,000 species occur.

    Look

    Although the different species may seem quite diverse at first glance, they do share some meta-level similarities in terms of body type and coloring.

    The adult animals are generally, i.e. in relation to the beetle world in general, of medium size and have an ovoid, sometimes more elongated, sometimes more rounded, domed shape. Their length is between one and 18 millimeters. In relation to the torso, their head is rather small, roundish and mostly set flush with the torso via a curved pronotum, so that a stocky appearance typically occurs.

    Many leaf beetle species are characterized by a striking, sometimes artistically patterned and often shiny metallic color. The magnificent leaf beetle is also a prime example in this respect: with its greenish-yellowish, blue to copper-colored changing, metallic shimmering colouration, which completely covers its body up to the legs and antennae, it almost looks like a jewel. Others, for example the golden earth flea, appear like a precious coin with their copper-gold, very shiny coloring. The potato beetle, on the other hand, impresses with its distinctive yellow and black striped pattern.

    way of life

    The adult animals usually mate several times with different sexual partners and produce several generations of larvae per year. The females lay their eggs individually or in groups or rows on the forage plants, depending on the species, often protected in shallow, gnawed hollows or covered under a layer of excrement. Some leaf beetle species also prefer to feed on aquatic plants. Their brood can therefore sometimes also be found under water in gelatinous shells.

    The larvae usually hatch after a few days and mature into adult beetles in pupations within a few days.

    The forage plants - and thus also the plants susceptible to infestation - differ depending on the leaf beetle species. Some are oliphagous, meaning they prefer only one or a few specific plants. This plant-relatedness is often reflected in the species name. In some species, it can cause immense damage if it occurs frequently. Colorado potato beetles can bare entire fields

    Relevant leaf beetle species for gardeners and farmers

    With the enormous variety of species of leaf beetles in Germany alone, we cannot describe them all here. We therefore want to focus on a few species that are of increased relevance for hobby gardeners and farmers. The following leaf beetles are frequently found here and play a major role as pests:

    • poplar leaf beetle
    • lily chicken
    • Colorado potato beetle
    • Red-necked Grain Chicken
    • lily leaf beetle

    Here is an overview of what they look like so that you can identify the pests, distinguish them from one another and take appropriate control measures:

    poplar leaf beetle lily chicken Colorado potato beetle Red-necked Grain Chicken lily leaf beetle
    shape ovate to rounded, stocky elongated, narrow pronotum, even narrower head Roundish, somewhat narrower, downwardly curved pronotum and head Elongated-narrow, pronotum of equal width, small head elongated-narrow, pronotum of the same width, small head
    coloring Wings brick red, head blackish to greenish, wings and legs black Wings and pronotum sealing wax red with a matt sheen, ventral side, legs and antennae black Wings lengthwise pale saffron yellow and black, pronotum spotted in the same colors, legs amber brown, feet black Wings glossy black with embossing, pronotum and legs maple syrup red, head and antennae black Wings dull light brown, rather crumpled surface, pronotum and legs pale amber, mottled with blackish, head blackish
    size 10-12mm long 6-8mm long 7-15mm long 4-4.5mm long 6-7mm long
    forage plants Poplars (aspens), willows Lilies, checkered flowers, chives Potatoes, tomatoes, eggplant, tobacco, peppers Wheat, Barley, Oats Water lilies, yellow water lilies, knotweed, strawberries
    combat Caterpillar flies, parasitic wasps,(18.99€) Rake up the ground under poplars in winter Collect, hose off larvae Toads, ground beetles, crop protection nets, bacterial preparation, neem oil Ladybugs, ground beetles, lacewings, parasitic wasps, assassin bugs Leaves of the host aquatic plant submerged for a long time
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    Fight leaf beetles

    The best way to protect your plants from leaf beetles depends on the type of leaf beetle and the extent of the infestation.

    poplar leaf beetle

    Poplar leaf beetles prefer to infest poplars

    Poplar leaf beetles can become a problem, especially in monocultures and in warm, dry years. Poplars along avenues are sometimes eaten bare and massive tree losses can occur. In particular, aspens are preferred by poplar leaf beetles, but willows can also be infested by them.

    Because poplar leaf beetles are not good flyers, the best way to prevent their infestation is to use mixed crops rather than monocultures. The beetles stay on a tree as long as there are leaves and move as little as necessary. Only when the tree has been eaten bare do they look for another one. However, if a suitable victim cannot be found soon, the beetles will starve to death while searching.

    If an infestation is already present, the best way to contain it is to disturb and, if necessary, kill the beetles that are wintering in the ground under the tree by raking up the soil.

    Only 6 agents based on pyrethrins, acetamiprid or thiachloprid are currently approved for control with insecticides.

    lily chicken

    The lily beetle is very eye-catching due to its strong colour

    The actually very pretty, sealing wax red beetles with the equally pretty name are the most common lily pests in Europe and Eurasia. They prefer to infest magnificent and giant lilies, but also checkered flowers or chives. As with most pests, the larvae cause the greatest damage because of their enormous feeding activity.

    Females deposit their orange-red eggs in clusters on the underside of leaves, where the larvae begin feeding after hatching. The infestation can be recognized by the signs of feeding, but also by the striking red imagines and the larvae covered with black faeces. They cover themselves with their droppings to protect themselves from predators.

    The most direct method of controlling lily beetles is to collect the adults, preferably in the morning when they are still stiff and sluggish. Because they let themselves fall when they are in danger and land with the more difficult-to-recognize, dark belly side up, it is also advisable to spread a net under the lily and shake off the beetles in a targeted manner. The larvae can be sprayed off the plant with a sharp jet of water.

    If the infestation is severe, insecticides will also help against biting and sucking pests.

    Colorado potato beetle

    The Colorado potato beetle is a serious threat

    The Colorado potato beetle originally came from central Mexico and later spread to the USA as a result of the large-scale cultivation of potatoes by white settlers. The pests were introduced to Europe via seed potatoes as early as the mid-19th century, initially to England and the Netherlands. Soon after, in 1877, the first specimens were also sighted in Germany.

    digression

    The invasion of the Colorado potato beetle

    In the course of the 20th century, Colorado potato beetles quickly became a real plague. In 1935, the so-called KAD, the Colorado potato beetle defense service, was even founded in the German Reich because of its invasive spread. He needed a Colorado potato beetle primer and mobilized school children and the unemployed to fight with the appeal:

    Be a fighter, don't be a sleeper, watch out for the Colorado potato beetle!

    Today, the Colorado potato beetle is widespread all over the world and can sometimes bare entire fields in a short time. Its preferred forage plants are of course the potato, on which it infests various parts of the plant. But other vegetables and crops belonging to the nightshade family, such as aubergines, tomatoes, peppers and tobacco, can also be affected.

    A number of methods can be used to control Colorado potato beetles. A combination of preventive and acute treatment measures is particularly helpful.

    preventive measures

    First of all, you should encourage natural predators of the Colorado potato beetle, which are now quite common in this country: these include toads and ground beetles in particular. When sowing and after germination, you should then cover your crops with crop protection nets. In principle, it also makes sense to strengthen the plants with a nettle manure spray treatment.

    After a year of infestation, you should dig up the soil well as a preventive measure for the next year, as the beetles overwinter in it. In this sense, it is also helpful to cultivate potatoes in crop rotation year after year. This is recommended anyway for a balanced land use.

    Acute Measures

    If the fat beetles are already running around in large numbers on the potato or pepper plants, it is best to collect them first. For larger crops, you can also walk through the rows armed with a stick and knock down the pests. Like many leaf beetle species, they like to fall when threatened and can then be collected in a net previously spread out on the ground. Mint broth or coffee grounds are supposed to drive the beetles away.

    The use of the bacterial preparation Bacillus thuringiensis, which is toxic for the beetle but not for humans and plants, can be quite effective. Neem oil, which is often used in organic horticulture, is also effective against Colorado potato beetles.

    Red-necked Grain Chicken

    The red-necked grain beetle loves wheat, barley and co.

    Because, as its name suggests, it prefers to eat cereals such as wheat, barley or oats, the grain beetle is a problem, especially for farmers. They also infest fodder grasses, occasionally maize. The larvae eat oblong holes in the leaves of the grass and can cause significant harvest losses.

    With natural predators, the red-necked grain beetle can be contained relatively well. Ladybirds, ground beetles, lacewing larvae, assassin bugs and parasitic wasps have an appetite for them. For certain moulting-inhibiting insecticides, a certain damage threshold, which is defined country-specifically, must be reached.

    lily leaf beetle

    The lily leaf beetle love aquatic plants

    Water lily leaf beetles belong to the aquatic plant-affine leaf beetle species. They are therefore particularly problematic for ornamental gardeners who maintain a pond with aquatic plants. Water lily leaf beetles not only infest the white water lily, but also other aquatic plants such as the yellow water lily, the water lily, the marsh bloodeye or the common arrowhead. But strawberries are also one of their forage plants, which is why they are also called strawberry beetles.

    The imagines and the larvae of the water lily beetle live on the leaf surfaces of their host plants and live there quite dangerously. They cannot swim or breathe underwater. Therefore, if you notice an infestation, the safest control method is to submerge the leaves. The larvae and possibly also the adult animals drown in the process.

    tips

    A longer immersion phase is the safest. To do this, you can weigh down the leaves with a wire mesh.

    frequently asked Questions

    What species of leaf beetle are there?

    In total, the leaf beetle family includes about 50,000 species. In Germany, however, only about 520 species occur. The most frequently represented of these are the magnificent leaf beetle, the Colorado potato beetle, the plantain leaf beetle, the poplar leaf beetle, the lily beetle, the common asparagus beetle, the tortoiseshell and willow leaf beetle or the hawthorn leaf beetle.

    How do I identify leaf beetle species?

    Some of the native leaf beetle species are easy to identify, some more difficult. The Colorado potato beetle or the magnificent leaf beetle are very easy to recognize with their pale yellow-black striped or bluish-greenish to copper-colored and shimmering violet coloration. The lily beetle is also very conspicuous with its sealing wax red back, but it can be distinguished from the similar-looking lily-of-the-valley beetle, whose underside is not black but also red. The flat, round, light green tortoise beetle variants, which are very similar to each other, are more difficult to identify.

    Are Leaf Beetles Pests?

    The Colorado potato beetle, the poplar leaf beetle, the red-necked grain beetle, the common asparagus beetle and the lily beetle are the most relevant pests in this country. They sometimes cause great damage in vegetable growing and ornamental gardens.

    Which measures are suitable for leaf beetle control?

    There are different ways to combat the different leaf beetle species. For the most common species, such as the Colorado potato beetle or the lily beetle, collecting or shaking off and catching the adults in nets is a common method. Larvae can be effectively sprayed off the plants with a sharp jet of water. Infested populations can also be contained by natural predators such as parasitic wasps, ground beetles, lacewings or ladybirds. In severe cases, certain bacterial preparations, neem oil or pesticides can be used as biological or chemical insecticides.

    How do I recognize leaf beetle eggs and larvae?

    The eggs of the leaf beetle species that are most common in our country usually sit in groups on the undersides of the leaves of their host plants. They have different colors depending on the species of beetle. The larvae also have their own appearance depending on the species. Those of the Colorado potato beetle, for example, have a squat, isopod-like ribbed body and a bright red color with spots on the sides. The larvae of the lily beetles are conspicuous because they are enveloped in their own dark faeces, which they use to protect themselves against predators. On the leaves they look like little piles of tar. The larvae of water lily leaf beetles stand out conspicuously from the green upper side of the leaves of the infested aquatic plants due to their black colour.

Category:

Animals in the garden